Internet Centre - Cost: $2500
On it's own, the Internet Centre is useless, but up to eight hackers can be sent inside, where their performance in hacking the internet is improved. Presumably they can use broadband and sitting down they can type faster ;)

Mines - Cost: $600
Purchasing this upgrade deploys mines around the selected structure, damaging and destroying any units that are unlucky enough to pass over them.

Neutron Mines - Cost: $500
Neutron Mines possess the unique ability to kill any infantry that is unfortunate enough to step foot on one or drive a vehicle over one, while keeping vehicles in tact. Driverless vehicles are free to be captured by you.